Airplane



R. F. HALL Amrum: riledmoct. 8, 1924 4 Sheets-Sheet 1 Oct. 13,1925. 1556,686

R. F. HALL AIRPLANE Filed oct. 8, 1924 4 shets-sheet 2 Oct. 13, 1925-` R. F. HALL AIRPLANE Filed Octv 8, 1924 4 Sheets-Sheet ,5

\ nlllllllllulllm-V/ HHIIIIIIIII Oct'. 13, 1925- R. F. HALL `AIHPLANE Filed Oct. 8, 1924 4 sneets-shezt 4 Ptented Oct. 1 3, 1925.

UNITED s'rATEs RANDOLPH F. HALL,

PATENT OFFICE-.

OF ITHAC, NEW YORK, ASSIGNOR OF ONE-FOURTH T0 THEODORE IP. HALL, OF WALLINGFO'RD, CONNEC'I'ICUT.

AIBPLANE.

Application fiiea oc'mber 8, 1824. tsemi'no. 742,400.

T 0 all wh-o'm, it 'may concemb:

Be it known that I, RANDOLPH F; HALL, a citizen of the United States of America, and a resident of I'thaca., county of Tompkins, State of New York,'have invented certain new and useful Improvements in Airplanes, of which the following is a specification.

This inve'ntion relates to certain' improvements inl airpla-nes; and the nature and objects of 'the invention will be readily recognized and understood by those skilled in the a-rts involved in the light of the following explanation land detailed description *of the accompanying drawings illustrating what I at present consider to be the preferred einbodiments or mechanical and aero-dynamical expressions of the invention from among;

various other forms, arrangements, combinations and constructions of which the invention is capable within the spirit and scope thereof.

The invention relates particularly to that general class of air planes capable of Vertical fiight through the action of revolving airscrews A,or propellers directly or indi- Vrectly developing the requisite Vertical lift for flight, 'and is 'more rticularly directed to the arra-ngement 'an mountin ofa plurality rof such :a-irscrews or prope lers on an airplane of this type and to' the solution of certain problems and the reduction of certan dangers encoun'red in the operation of a. multi-propellered airplane of cal lift or flight type.

Where a plurality of propellers are emw ployed fora Vertical lift type of airplane, there a-retwo general mounting arrangements which can be followed, either a tandem mount-ing' of 'the propellers along the Vertical axis of the airplane, o'r a mounting and disposition ofthe propellerslaterally at opposite sides of the longitudinal axis of the airplane, asF will be understood by those fanliliar with this art. The lattel: mounting is more eflicient aerodynamically than the tandem mounting of the airscrews or propellers; but /presen certain problems and resultsin certain inherent dangers in Z operation and use of an airp'lane having the' pro-mllors so disppsed and mounte'd thereon." Wit-h 'the propel ers mounted laterally at opp'osiie sides 'of the 'longitudinal axis of the vertithis type of'airplane is a serious hazard and' presents lone of the'problems and obstacles encountered with thel use of the more efficient` lateral monnting and disposition of airscrews or propellers on opp'osite sides of theflongitudina-l axis of the airplane to develop the Vertical lift for flight thereof.

' The present invention has as one of the main and fundamental'objects thereof, a solution of the foregoing problem and. the substantial elimina-tion of the hazard and danger in flight with pro'pellers mounted at opposite sides of the longitudinal or fore and aft axis of a Vertical lift airpla-ne; resulting from the failure of a' propeller or the drive niechanism therefor, on one side of the a-irplane yand the creation or establishto a propeller at oneside of the airplane.

i A further object of 'the invention is the provision in an airplane of the Vertical lift type having. propellers disposed atl opposite sides of the/longitudinal axis-of the .airplane, for automatically rendering a propeller at one side of the airplane inoperative l vupon failure of a; propeller at the' opposite side of the' airplane, in order to prevent the w creation of an unbalanced couple and resulting loss of flight equilibrium.

A finither object of vtheinvention is to .provide for autoi'natirally Cutting ofl' the power dehvered to 'an mrplane propcller upon fail'ure of the 'propeller, so as to pre- Vent dam'age to the drive mechanism or power unit tlierefor, through oontinued operation of a broken propeller,

A further object of the inventioni is the provision of means controlled by the slipstream of an airplane p'ropeller for cutting off tlie ignition of the power unit driving the propeller and stopping the power, upon failureof the propeller or drive mechanism thereof.

Another object of the invention is to provide in an airplane of the Vertical lift type having propellers mounted at opposite sides of the longitudinal axis thereof, a propeller drive mechanism which will cause continued operation of the propellers at both sides of the airplane upon failure of the drive mechanismto a propeller at one side, and to pro- Vide means for automatically rendering a propeller at one side of the airplane inopei'ative upon failure in a propeller at the other side thereof, so as to practically eliminate the possibility of creating' an unbalanced couple and loss of equilihriun'i of the airplane in fiight under any condition of failiire in eitherthe propeller drive mechanism or the propellers.

A further object of the invention is to provide certain iinprovements in design, construction and mounting of the mechanism and Various elements forming the same, for carrying out the objects and securing the results of the invention, which will be efli- 'cient and positive in operation under the varying conditions encoiintered in use and operation.

With the foregoing general objects, and certain other objects and results in view which will be readily apparent to and understood by those skilled in the aeronautical art from the following explanation, the invention consists in certain novel features in construction andin combinations and arrangements of elements, as will be more fullyl and particularly referred to and spccified hereinafter.

Referring to the accompanying drawings, in whicli similar reference characters refer to corresponding parts throughout. w

Fig. 1, is a perspective view, more or less schematic or diagrammatical, of a Vertical lift airplane having propellers mounted at opposite sides of the longitudinal axis and operated from a power unit through the medium of drive mechanism embodying the invention and having means of the invention for Cutting off the power unit upon failure of a propeller, those elements of the propeller drive, power mechanism, and power control mechanism being shown in full lines, while the airplane is purely diagrammatically indicated in dotted Outline.

Fig. 2, is a more or less diagrammatical view in side elevation of a type of Vertical lift airplane in which the Vertical lift is indirectly developed from the propellers, with the Various features of the invention embodied therein and applied thereto, parts of the airplane being shown in dotted outline. i

Fig. 3, is a View of the automatic power plant cut-out switch of the invention, the casing tlierefor being shown in Vertical section.

Fig. 4, is a View in longitudinal section through the slip-s'tream operated centrifugal switch of the invention, and showing the wind wheel driving member tlierefor.

Fig. 5, is a transverse section through the centrifugal switch taken on the line 5-5, of 'Fig. 4.

Fg. (i, is a detail fragmentai'y view of the centrifugal switch housing showing certain of the switch connecting posts.

Fig. 7, is a schematic View of the electrical connections between the power plant, aiid switches embodied in the invention.

Fig. 8, is a detail View in elevation showing the operative conneotions between one end of the auxiliary or balanced drive of the invention and one of the propellers of an airplane.

While the invention is primarily adaptcd to use with airplanes of the so-called Vertical lift types. and in the examples of tlie invention disclosed hci'ewith is presented as applied to and embodied in such types, there are certain features of the invention which are capable of general application to similar or equivalent airscrew or propeller mountings and arrangements and to the drive mechanism tlierefor on other types of aircraft. The ineclianical and aerodynaiiiical expressions of the invention illustrated and described herewith as applied to aii'planes of the Vertical lift types, are presented purely by way of example and not of limitation, because the problems and disadvantages overcome by the invention are encoiintcred in a high degree with siich types, and heiice sei've to more clearly bring out the principles and features of the invention and the results attained thereby.

In Fig. 1 of the accompanying' drawings a Vertical lift type of airplane is pui'ely diagrammatically indicated in dottcd outliiic to represent any desired design or type of airplane in which Vertical lift is developed directly from the action of revolving air` screws or propellers, and embodies a body `or fu'selage 1 having control sui'face's 2, and

Vanes or wings 3 all arranzed and disposed in a 'more or less conventional manner to typify this general class of airplat'iis. A motor or power unit M is mounted 'on the body 1 at any desired point, in the present instance within 'the forward portion of the body in the usiial manner, and airscrews or propellers P are mounted at opposite sides of the' body above the vanes or wings the body,.'fand are s aced 'laterally at 'equidistant points from tie longitudinal or fore andiaft axis of the airplane. These airscrews or propellers P are rotatedand driven i asubstantially horizontal plane' from the motor M, 'to develop the requisite direct Vertical lift for Vertical filght of the airplane, as will be readily understoodl by 'those familiar with this type of airplane.

' in bearings .12' (see Fig. 8.) within the housings 12, respectively, the propellers P being fixed in any suitable or desired manner on the upper 'ends of the shafts above housings 12 for rotation by these sha'fts. The bearings in lower housi'ngs 11.

vare similar to bearings 12' in housings 12. A s stem of 'bracing is provided between the ody of the airplane and the shafts 10 and housings in which mounted to maintain these shafts with the propellers Pin rigid position and transmit the forc'es to which subjected to the airplane structure. In this instance this system embodies `an arrangement of brace and -strut members 14 extending between the shaft housings 11 and 12 and the airplane structure, as will be v clear by reference to Fig. 1 of the drawings 7 without requiring a detailedp description thereof, any desired arrangement suitable` to the particular typeof airplane being em- I 'ployed.

' The-propeller shafts 10 are driven in any suitable manner from the motor 'orpower unit'tM, and. in the example herewith an arrangement of shafting and gears is em- .ployed for transmitting the power from the motor to the propellers P and shafts 10.

A shaft 15v extends rearwardly from theA motor lM, either as an extension ofl the motorv power or crankshaft or a separate shaft. coupled thereto, and a transversely disposed shaft 16 is munted extending between the lower-ends of 'the propeller shaftsl 10. The power shaft 15 is operatively connected with the shaft 16 through the me-- dium of worm gearing (not shown) within the gear casing 17, and the opposite 'ends of the '-shaftv 16 are provided with worm gears (not shown) within the gear casings 18, which casings are connected with and fixed'to the 'housings 11 atv the lowerends of the shaft 10, respectively. A worm gear` (not show) is fixed on the lower endof each propeller shaft 10 within the housing 11 thereof, and' is arranged in operative 'engagement with the gear in the casing 18 on the adjacent end of shaft 16, these en- I gaged worm gears are formed to operatively plane is-eliminated by couple the opposite ends of shaft 16 with the propeller shafts 10 in such a manner as to rotate shafts 10 and propellers P thereon in -opposite directions. VVith the foregoing arrang'ement of drive mechanism, the propellers P are rotated or revolved in a substantially horizontal plane in opposite directions to develop' the requisite Vertical lift, by the .motor M, through shafts 15 and '16 and the gearing operatively coupling the same. The gearing is preferably of 'the worm type, although not so limited, and, of usual conventional formation well known in thearts, so that it has not been deemed necessary to make a disclosure of such gears, and particularly in view of a disclosure hereinafter of such gearing which is adapted for use in operatively connecting the prof peller shafts 10, and shaft's 15 and 16.

A Vertical lift type of airplane embodying the foregoing general type of propeller mounting and arrangement andv the drive mechanism therefor, is subject in flight to .the possibility o'f failure in the drive mechanism to one of the propellers 10, in which event an unbalanced couple will be set 'p upon stoppage of the propeller at one side of the longitudinal axis of the airplane and 'the necessary equilibrium of the airplane destroyed with possible resulting loss of flight control. According to the invention the above possibility with this type of airroviding an auxiliary drive mechanism orming a balanced drive for and between. the propellers P, so that failure in oneside of the main drive will not result. in stoppage of the propeller` connected therewith.

This auxiliary balanced drive embo'dies a. shaftl 20 extending between and operatively connected' with the propeller shafts 10 at the upper or propeller ends thereof. Each propeller shaft 10, referring now to Fig. 8 in particular, is provided with a worm gear 21 fixed thereon within the bearing vhousing -12 between bearings 12' at the upper end of the shaft, and the adjacent end of auxiliary drive shaft 20 is provided with a worm gear or pinion 22 in operative engagementwith the propeller shaft gear 21. A gear casing 273 is secured to, or formed-as a part'of, each housing 12, toenclose gear 22 in mesh with gear. 21, on the adjacent end of shaft 20. 'Preferably a center bearing 24 is providedl for the auxiliary or balanceddrive shaft 20, and is suitably braced and supported from the body 1 by the bracemembers or struts 14 (see Fig. 1). The engaged setsof gears .21-22 operatvely connecting the opposite readily understood. Gears' similar to 21 and 22 canbe employed for operatvely connecting the ends of shaft 16 with shafts 10, and can be similarly arranged within the housings 11.

In normal fiight With the propellers P rotated by shafts 10 from the motor lV, the shaft 20 is rotated by the shafts 10 and forms an auxiliary connecting drive mechanism therebetween. e Now, if a failure occurs in flight to the drive mechanism for one of the propellers P While permitting the propeller on the opposite side of the airplane to operate, the auxiliary shaft 20 Will transmit power from the Operating shaft 10 and rotate the propeller P at the opposite side of the airplane in the reverse direction, so that both propellers are rotated With an equal distribution of power therebetween and the creation of an unbalanced couple through stoppage of a propeller on one side and continued operation of a propeller on the opposite side of the airplane is prevented. By the auxiliary balanced drive the possibility of loss of equilibrium and control in flight through failure of the drive to one of the laterally mounted propellers is substantially eliminated. In the event of complete failure of the drive with stoppage of both propellers, the condition referred to Will not be present, and descent Without power, according to the particular type of Vertical lift airplanes can then be made.

Another failure condition is possible with a propeller and drive mounting and arrangement of the foregoing general type, which Will result in` the creation of an unbalanced couple and loss of equilibrium in fiight, namely,'a failure in a pro'peller, per se, and the invention provides for eliminating the results of such a failure by automatically Cutting off the power driving the propellers, so as to prevent operation of a propeller on one side of the airplane With a propeller on the opposite side of the airplane aerodynamically inoperative. According to one mannet' of carrying out this feature, the invention provides mechanism Controlled by the slipstream of each propeller for cutting off the ignition circuits, Where an internal combustion motor power plant is utilized, upon failure of a propeller, so as to stop the power and render the propellers on both sides of the airplane inoperative.

lVith the propellers mounted and arranged as shown in the instant example, and driven from a single motor or power unit, the mcchanism for Cutting off or grounding the motor ignition circuits includes switch members mounted in position to bo acted upon and controlled independently by the slipstreams from the respective propellers P. Referring to Figs. 4 to 0 inclusive, of the acconipanying drawings a design and construction of centrifugal switch is shown operated by a Windwheel or screw, adaptcd for the purposes of this feature of the invention. The switch member 30 embodies a. streamline holloW casing 31, of any suitable non-conducting material having one end thereof open, and close-d by a cap meinber 32 threacled into the end of the casingI 21 and forming a support and bearing member for a shaft 33 which extends centrally ther-ethrough and is journaled in a bearing 34 carried thereloy. The shaft 33 extends longitudinally through the. interior of casing 31 and is journaled in the reduced closed end portion thereof in a bearing The reduced end of the casing 31 is provided With a longitudinal bo're therethrough axially alined With shaft 33, and a carbon or other suitable conducting material contact plug 30 is disposed in tiis' bore and niaintained in engagement With .the end of shaft 33 by a coil spring 37 under compression between the outer end of the plug and au exterior cap 38 over the reduced end o-f casing 31 closing the bore therethrough. The cap 38 is provided With a screw 39 extending therethrongh in contact with the spring 37 for connection With an electrical conductor, such as a Wire, cable 01' the like.

A contact ring 40 is mounted Within the msiiig 31 extending therearound at the reduced end thereof, adjacent the bearing of the shaft 33, and is suitably fixed to the inner wall of the casing. A stud portion is formed extending from the ring out- Wardly through the casing wall, and carries a screw forming a binding post 41 on the exterior of the casing for making electrical connection With the ring. A contact nieniber embodying a pin 42 slidably mounted in a. bore formed transversely` through the shaft 33 Within the plane of or alined with the contact ring 40, is provided for movement to and from electrical contact With the rinfr 40. `A contact shoe 43 is fixed on out` end5 of the pin 42 for movement therewith to and from sliding electrical engagement Withthe contact ring 40, and a coil eXpansion spring 44 is mounted over pin 42 bctween shoe 43 and the shaft 33, normally forcing the contact shoe- 43 into engagement with ring 40. The opposite end of the pin 42 is provided With an enlarged cross head 45 of suflicient- Weight to be acted upon by centrifugal force upon rotationof shaft 33, as lwill be explained hereinafter.

The shaft 33 is extended adistance out- Wardly beyond the casing 31 and end cap 32` and a small Windmill propeller or 'indwheel 46 is mcucted thereon, in the u-ual or any other desired manncr, as by the retaining cap 47 threaded onto the outer end of the shaft. An annular ring 48 having a flange extending therefroni is mounted on the Windwheel 4G, With the fiange extendof air upon the windwheel. Upon rotation` of shaft 33 at a. suflicient speed, dependent upon the strength of coil spring 43, the centrifugal force created acts upon weighted cross head and ca-uses lt to move outwardly from shaft 33, which slides the pin 42 through the bore in the shaft and withdraws contact shoe 43, against the tension of spring 44, out of engagement with contact ring 40. W'hen the speed of rotation of shaft 33 decreases below a predetermined rate, the spring 44 overcomes the decreased centrifugal force acting upon pin 42 and crosshead 45, and forces the contactr'shoe outwardly. into engagement with contact ring 40. The position of pin 42- and cross head 45, with contact shoe 43 out of engagement with ring 40, is indicated in dotted outline in Fig. 5 of the accompanying drawings` and the operation of the switch will be clearly underst'ood by reference thereto.

In the example illustrated in Fig. 1. of the drawings, a switch member 30 is mounted in vcrtically disposed position below each of the propellers P, with the windwheel 46 thereof uppermost and located within 'the slipst-ream of the propeller P thereabove so as to be rotated' thereby and cause the contact shoe 43, through'shaft 33 and pin 42, to move out of engagement with rlng 40.` These slipstream actuated switch members 30, are electrically connected with' and control a magnetic switch 50, orequivalent element, which is in turn connected in the magneto' o-r ignition circuits lof the motor M, so as to| render the ignition circuits inoperative through operation thereof by switch members 30, under certain conditio established b'y the propellers P.

The power plant or motor control member in the present instance is inthe form of a magnetic switch, reierring now to F'ig. 3 of the drawings, connected in the magneto circuits of motor M, and includes a casing or housing 51, in the upper portion of which electro-magnets 52 and 53 are mounted disposed horizontally in longitudinal or axial alinement with the adjacent ends.

thereof spaced apart. Magnet 52 is electrically connected with binding posts 52a and 52h, and magnet 53-is electrically connected with binding posts 53a and 53 all mounted on the upper side of casing 51 and accessible onthe exterior of the casing.

A contact arm 54 is piyotally'mounted in vertically disposed position intermediate the magnets 52 and 53, and extending upwardly therebetween for swinging movement or oscillation toward and from these magnets, respectlvely. The'contact arm is pivoted interlmediate the ends on a suitable pivot 55,

and thus forms the upper contact arm 54 and the lower or depending contactarm 56. A pair'of contacts 57 and 58are mounted disposed at opposite sides, respectively, of

the upper contact arm 54, and a similar pair i o f contacts 59 and60, -are disposed at opposite sides, respectively, of the lower contact arm 56. These contacts are so mounted and arranged with respect to the contact arm 54 that with the arm swung toward magnet 52 contact 57 is engaged and the .lower arm 56 engages contact 60, whilewith -ing open the catches to release the arm 56.

The contact arms 54-56 are maintained in normal vertically disposed position. with arm 56 midway between magnets 52 and'53, by a pair of coil Springs 63 extending ,from opposite sides of the arm and secured at fixed points in the casing, `so that upon release of the arm 54 from either position swung from the `Vertical, the spring 63 on the side opposite from the direction in which the arm is swung will draw or pull the arm back to normal position.

' Exterior binding posts 57a and 58a are mounted at opposite sides of casin 51 on the under or lower wall thereof. ostt57a is connected with the upper and lower con- 'tacts 57 and 59 by wires 63' and 64, respectively, and post 58a-is connected-with the upper and lower contacts 58 and 60 by the wires 65 and 66, respectively. A single pole single throw knife switch 67 is mounted at one side of the casing 51, with one' side thereof connected by wire 68 with exterior binding post 67a mounted on the 11 per wall of casing 51, and with the other si e thereof connected by wire 69 with the magnetic switch contact arms 54-56.

The motor M for driving the propellers P of Fig. 1, is of the double ignition type embodying two magnetos 70 connected with the usual cockpit switch S by wires 71 (see Fig. 7 all of the usual or other suitable types arranged in the conventional manner familiar in this art. .In Fig. 7 of the accompanying drawings, the manner of electrically connecting the ignition system of the motor M with the magnetic' switch 50 and the slipstream Controlled centrifugal switches 30, is purely diagrammatically disclosed. The magnetic switch 50 is suitablyL mounted in the body 1, or at any other desired point and is electrically connected with the ignitionu circuits of motor 'M through the switch S. Contact 71a of switch S is connected by Wire 72 with binding post 57a, and contact 71h is connected by Wire4 73 With binding post 58a, of the magnetic switch 50. Switch 50 is connected to ground G by Wire 74 from binding post 67a, and switch S is connected to ground by Wire 75 from contact 71 to Wire 74. Batteries B and B' are provided for energizing the electro-magnets 52 and 53, respectively, of switch 50, although any other desired source of electrical energy may be employed for this purpose. One terminal of battery B is connected With one terminal of electromagnet 52 by Wire 7 6 through binding post 52b of switch 50, and one terminal of vbattery B' is connected to one of the terminals of electro-magnet 53 by Wire 77 through binding post 53a.

The centrifugal switches 30 are mounted, as hereinbefore referred to, so as to be operated by the slipstreams from propellers P, respectively. These switches 30 are electrically connected in the, circuits to the electro-magnets of magnetic' switch 50 and control the operation of this switch. Contact or binding post. 41 of right hand switch 30 is connected by -wire 78 With a terminal of battery Bf, and contact 39 of this switch 30 is connected by Wire 79 With binding post 53b for electro-magnet 53 of switch 50. The left hand centrifugal switch' 30 is connected from contact or binding post 41 thereof with a terminal of battery B by Wire 80, and is connected with binding post 52EL for electro-magnet 52 by Wire 81 from contact 319 thereof. In the wires 79 and 81 are placed switches 79' and 81', respectively, so that the circuits from batteries B and B', through centrifugal switches 30 to the electro-magnets 52 and 53, respectively, can be opened when the system is not in use.

The operation of the foregoing system for controlling and cutting off the power driving the airscrews or propellers of a Vertical lift type of airplane, as in the example herewith, upon the establishment of certain propeller conditions in fiight, is as follows. With the 'airplane not in use, the switches 79' and 81' are opened to open the battery circuits to the electro-magnets of the magnetic switch 50. Preparatory to use or fiight of the airplane, switches 79' and 81' are closed, and the centrifugal switches 30 are likewise closed, the contact shoes 43 thereof being in contact With rings 40, and

closed circuits from the batteries B' and B' closed circuit* energize electro-magnets 52 Vand 53,- but as they are so designed as'to exert an equal magnetic force, the contactv arm 54l disposed vertically Vand midway therebetween, will have an equal force exerted thereon at opposite sides thereof and will hence remain in normal iifoperative position` The motor ignition switch S is then closed and motor' M started and operated in the usual manner. Upon operation of motor M, the airscrews or propellers P are reyolved and result in rotation of centrifugal switches 30, through lthe action of the pro-- peller slipstreams upon the switch windwheels 46 which lie Within the slipstreams from propellers P, respectively. Rotation of the shafts 33 of centrifugal switches 2-30 at the proper rate of speed, causes centrifugal force to slide the pins 42 through these shafts and withdraw contact shoes 43 from electrical engagement with the fixed contact rings 40. Preferably, although not so limited, the Springs 44 on pins 42, are of sufficient tension or strength to prevent Withdrawal of shoes 43 from rings 40, until propellers P are rotated at a rate above the usual rate at which idled in warm'ing up the. motor M. Further, it is dcsirable that the Springs 44 be of as near the samecstrength and exert the same tension as practically possible. Thus, when switches 30 are operated at the required r'at'e of speed, the cirmagnets 52 and 53, are broken or opened and these magnets are deenergized. However, due to the opposite springs 63 on contact arm 54, this arm is still maintained in normal Vertical position midway between the magnets 52 and 53. In the foregoing manner by the arrangement of the system as described, the magnetic switch 50 is maintained in normal inoperative condition with both propellers P either Operating or not operating, as long as the condition of both propellers is the same.

With the airplane in flight, the centrifugal 'switches 30 are open, as previou'sly explained, and electro-magnets 52 and. 53 are deenergized, with contact arm's 54-50 maintained in Vertical inoperative position' by the springs 63, of the magnetic switch 50.

Now, assume that during flight a failure occurs in the right hand propeller P with the resulting cessation of the slipstream therefrom, or a decrease below av certain predetermined force, then rotation of the right hand centrifugal switch Windwheel 4,6 stops or decreases below a predetermined point, and the centrifugal force acting upon pin 42 to maintain shoe 43 out of contact with ring 40 is removed, so that spring 44 si'- -cuits from batteries B and B' to electroshoe 43 outwardly into electrical engagement' switch 30.

with the contact ring 40 of this right hand lEn,; ,0'agement of shoe 43 with ring .40 of switch 30, closes the circuit from battery B' through wire 7 8,- and contact 41, ring 40, shoe '43, pin 42, shaft' 33, plug 36, spring 37, and contact 39 of the switch 30; wire 7 9 from switch contact 39 to the elecvtro-magnet- 53 of switch through contact 53h, andthen from magnet 53 through contact 52, back to battery B' by wirel 77 (sec Figs. 7 and v8). Closure of the foregoing circuit by switch 30 energizeselectro-magnet 53, and the left hand propeller P being operative, the left hand switch 30maintains the circuit to electro-magnet 52 open and this m'agnet ideenergized, so that energized magnet 53 magnetically attracts or draws the upper contact arm 54 of switch 50 toward the right and swings the same into ,engagement with contact 58 against the tension of left hand spring 63, and at the same time arm 5G is swung to -the left, being below pivot 55, into engagement with contact 59. In this position contact 'arms 54-56 bridge and electrically connect the contacts 58 and 59, and are maintained in this position by' the lower end of armp56 snapping into the adjacent spring catch 61 which s'eeu-res'the contactarms against the tension of spring 63 into operative position.A The electrical connection of contacts 58 and 59 results in short circulating or 'grounding the ignition ci-rcuits of motor M and stops operation of the motor. This is accomplished by closing and completing a circuit from the magnetos 70, through cockpit switch S and contact-s 71a and 71b thei'eof, wires 72 and 73 to binding posts 57a and 58a and contacts 59 and 60, respectively, of the magnetic switch 50. The circuit is continued from contact 59 through contact arms 54-56 to ground G through Wire 69, closed switch 67, Wire 68 and binding post'67a, and wire`74, and is continued from binding post 58* by wire'65 ,to contact 30 uponv failure of y the slipstreain of which controls switch 30,

58 and contact-arm 54. p

The operation of magnetic switch by closing of the right hand centrifugal switch right hand propeller P,

grounds the ignition circuits of motorM and stops operation of the motor and rotation of left' hand' propeller P. Thus, the

` establishment of an unbalanced 'couple due to stoppage of the right hand propeller and` continued operation of the left hand propeller, of the laterally mounted propellers P, is prevented and the resultindpossihilit-y of loss of lateral equilibriuin and flight 'control eliminated. A failure the left hand propeller P will likewise result in stopping motor M. by closing left hand switch 30, 'through the' circuits for grounding the `motr in a manner'similar to that described with reference to a 'failure in the right-hand propeller, and will be clear and understood 7 by reference to Fig. '7 of the drawings'. The

loss of equilibrium in flight by. failure in either of the laterally mounted .propellers P is thus prevented by the foregolng system of the invention, and in connection with the v hereinbeforc ,described auxiliary 01' balanced drive for the propcllers' P, renders an air-. plane so equipped free of the inherent hazard or danger in flight occasioned by either a failure in a propellerV per se, or in the drive Imechanism thereto. The knife switch 67 provided for the motor control system is utilized to renderthc entire system inoperative, if desil'ed, but is normally maintained closed, the switches 7 9' and 81' being used to temporarily render the system inoperative;

A different v type of vertical lift airplane is purely diagrammatically disclosed in Fig. 2 of the drawings, with the auxiliary or balanced drive mehanisn'l and the motor con-- trol system features of the invention applied thereto and embodied therein. In this type of Vertical lift ai1'plane,'the laterally disposed propellers P are mounted vonvthe propeller shafts 10, which latter are disposed at a forward inclinationand angle to x the Vertical. and a Wing cellule 3' is disposed rearwardly in the slipstream from propellers P, so as to be acted upon thereby and. with the propellers P develop the requisite vertical liftin flight. T his type may be aptly termed, and is here disclosed to exemplify, an air cr'aft of' the indirect Vertical lift type, .in which the Vertical lift is indirectly derived and developed from rotating air screws or propellers. vIn the type shown in Fig. 2, the arrangement of propeller drive mechanism from motor M, in-

-cellule 3', and a feature of the invention in Cooperation with the' drive mechanism' and motor control system, resides in arrarging the center of gravity and gravity vforce vector 101 forward of the'wing cellule vector 102. so that upon removal of the propeller thrust shown by vector 103. the fiat plate` resistance of the wing cellule 3' will roduce a moment about the center of gravlty which will place the airplane in' a gliding attitude and also create a forward mo- :if

ition. 'control system of the invention to stop mo- T hus, upon operation of the inotor of units may be employed, for instance an independent unit may be used for driving each airscrew or propeller employed. i

IVith reference to that feature of the invention providing for the automatic Cutting ofi1 or stopping of the power driving the propellers upon the development of certain propeller conditions in fiight, attention is w directed to the fact that the invention Contemplates and includes other arrangements and means for this purpose Controlled by a propeller or propellers to stop the power driving the same, and by the present disclosure it'is not intended to limit the invention to a centrifugal form of switch Controlled by the slip-stream, or -to the manner of stopping or rendering the power unit inoperative. If desired or found expedient, other means Controlled from a propeller or the slipstream thereof can be employed, as well as other methods of stopping or Cutting off the power, than but Cutting the ignition circuits of an internal combustion type of power unit, without stepping beyond the Confines of the b'road principles exemplified by the present mechanical and aerodynamical expressions of this feature of the invention. vFurther, this feature of the invent-ion is adaptable to airscrew or propeller driven types of air- Craft generally, and Can be applied to a power driven propeller to stop the power applied thereto upon failure in the propeller or drive, so as to prevent continued operation of a propeller or the drive mechanism therefor after a failure therein and resulting damage from such continued operation, as will be readily recognized by those skilled in' this art.

The examplos of the invention illu'strated and described herewith disclose Vertical lift types of airplanes embodying two laterally mounted propellers, but it is to be understood that the various features of the invention are applicable to aircraft employing' any desired number and arrangement of airscrews or propellers and Can be embodied to functionwith all of such arrangements of multiple propellers-or any number thereof.

It is also C-vident that various other forms, arrangements, modifications and substitutions might be resorted to without departing from the spirit and scope of my invention, and hence I do not wish to in any wayl limit myself to the exact and specific disclosures hereof.

Desiring to protect my invention in the broadest manner legally possible, what I claim is:

1. In aircraft, a plurality of propellers, a power plant, a main drive mechanism from said power plant to each of said propellers, respectively and an auxiliary drive mechanism connecting the main drive mechanism to said propellers, said auxiliary drive operative to drive any one of said propellers upon failure in the respective main drive mechanism therefor.

2. In aircraft, a plurality of propellers, a main drive mechanism for each of said propellers, and an auxiliary drive mechanism connecting and operated by said main drive mechanisms,`said auXiliary drive operative to drive a propeller upon failure of the main drive therefor.

3. In aircraft, a plurality of propeller" shafts, propellers mounted on said shafts, and an auxiliary drive shaft Connecting and operatively coupled to said propeller shafts adjacent the propellers mounted thereon, respetively, said auxiliary shaft operative to drive anyone of said propellers upon failure of the shaft therefor, from the remaining propeller shafts with which connected.

4. In aircraft, a pair of propellers, separate main drive mechanism therefor, and an auxiliary drive mechanism extending between, operatively coupled with, and driven by said main drive mechanisms.

5. In combination, propeller shafts, a propeller on each of said shafts, a power unit for Operating said shafts, and an auxiliary shaft operatively coupling said propeller shafts and driven thereby.

G. In combination, spaced, substantially parallel driving shafts, propellers on each shaft adjacent one end thereof, a power unit operatively coupled with the opposite ends of said shafts for driving the same, and an auxiliary shaft operatively connecting and driven by-said driving shafts adjacent said propellers.

7. In combination, substantially parallel drivin,r shafts having driven members at one end thereof and the power applied at the opposite ends thereof, and an auxiliary drive shaft operatively connecting and driven by said driving shafts, intermediate the points of power'application the-reto and the members driven therefrom.

8. In an aircraft propeller drive, spaced snbstantially parallel propeller shafts, propellers mounted on said shafts adjacent one end thereof, a power unit operatively lcoupled with said shafts adjacent the opposite ends thereof, and an auxiliary drive shaft extending between and operatively` connected with' said shafts adjacent the propellers mountcd thereon.

9. In anaircraft propeller drive embodying spaced propeller shafts, propellers driven therefrom, and a source of power forl 10. ln an airplane, propellers. inounted' latei'ally of the longitudinal axis thereof, propeller shafts for said propellers, respectively, drive mechanism for each shaft and propeller, and' an auxiliary drive extending' between, operatively coupled with' and driven by' said propeller shafts, the said auxiliary drive' adapted to 'operate a propeller upon failure of the drive 'mechanism thereto, from. an operative lpropelled shaft with which coupled.

11. In an airplane, propellers mounted :a L-thereon laterally of the longitudinal axis 30 thereof, drive mechanism for each propeller, and an auxiliary drive operatively connecting said propellers and driven from and by said propeller drive mechanisms, the said auxiliary drive operating a propeller upon failure, of the drivemechanism thereof',

from an operative propeller drive 'mechansin by which driven.

12. ln an airplane, propellers mounted thereon laterally of the ilongitudinal 'axis thereof, spaced substantially parallel propelle-r shafts for rotating said propellers, respectively, a power unit, drive mechanism from said power unit to said propeller shafts, and an auxiliary drive shaft extendingbetween and operatively connected with and driven' by said propeller shafts adjacent' the propellers rotated thereby.

13. I'n an airplane, propellers mounted i thereon laterally of the longitudinal i axis thereof, spaced approximately parallel propeller shafts forrotating said propellers, a

drive mechanism for each propeller shaft and propeller for ,rotating the same in opposite .directions, and an auxiliary drive shaft extending between and operatively coupled with said oppositely rotated propeller shafts and driven thereby' adjacent the propellers operated by said shafts.

14. In an aircraft propeller drive, spaced approximately parallel propeller shafts, propellers mounted thereon for rotation thereby, a power` unit, drive mechanisms connecting said power unit with said propeller shafts'for rotating the same with the propellers thereon in opposite 'directi0ns, a

gear on each propeller shaft adjacent the propeller thereof, and an auxiliary drive shaft extendin between said propeller shafts and provided With gears thereon operatively coupling said shaft with the oppoby the propeller slipstream for cutting off `the powerv driving said propeller upon failure of the propeller slipstream.

16. In aircraft, a ropeller, a source of power for driving sai controlled by said propeller for cutting off the power delivered thereto upon failure of the propeller. w'

'17. In'aircraft, a propeller, a source of power driving said propeller, land means controlled by the rate of speed at which said propeller is driven for cutting ofl the power' driving the same when the propeller speed drops below a4 predetermined rate. 18. In airraft, a ropeller, a source of power for driving said propeller, and means disposed Within and controlled 'by the slipstream of said propeller for cutting ofi the source of power driving the same when the slipstream reaches a` predetermined force.

19. In. aircraft, a propeller, an internal propeller, and means combustion motordrivmg said propeller,

a cut-out switch therein, and means controlled by said propeller slipstream for operating said switch.

22. In aircraft, a propeller, an internal combustion motor driving said propeller, the said motor including ignition circuits having a switch therein, and means controlled by the propeller slipstream for Operating said switch, said means inoperative during normal flight operation of said propeller and rendered operative lto cause said switch to open the ignition circuits and stop said motor upon decrease in the propeller slipstream below a predetermined force.

23. In aircraft,v a. plurality of propellers, and means controlled by said propellers 'for rendering all of them inoperative Vupon failure in operation of 'any one of them.

24. In aircraft, a\plurality of power lis driven propellers, and means controlled by each of said propellersfor Cutting off the power andv rendering all of said propellers inoperative'upon failure in operation of any of the said propellers.

25., In aircraft, a plurality of propellers, a source of power for said propellers, and means controlled by each propeller for cutting of the power for all of said propellers upon failure in operation of any of the said' slipstream of each of said propellers for.

Operating said switch to ground the ignition circuits of 'said power plant and' stop the operation of all of said propellers upon failure in' operation of any of them and resulting substantial cessation of the slipstream therefrom, respectively.

' 28. In aircraft, a plurality of propellers, an internal combustion motor for driving said propellers, an ignition system for said motor including electrical circuits therefor,

a switch connected in said circits for' grounding the same to render the motor inoperative, and means Controlled by the slipstream of each of said propellers for operating said switch to ground the motor ignition circuits upon failure of an)v one of said propellers and the slipstream thereof.

29. In an airplane of the Vertical lift type, propellers disposed laterally of the horizontal axis ofithe airplane, a power plant for driving said propellers, and- \means for rendering said power plant inoperative upon failure of one of said laterally disposed propellers.

30. In an airplane of the Vertical lift type, propellers disposed laterally of the horizontal axis ofithe airplane, a power plant for Operating said propellers, and means disposed in and 'Controlled by the slipstream from each propeller for rendering the power plant inoperative to stop the operation of said propellers,l the said slipstream controlledmeans operated to render the power plant inoperative by aerodynamplc failure of the propeller and resulting substantial cessation of the slipstream therefrom.

31. In an airplane of the Vertical lift type, propellersV mounted laterally of thehorizontal axis of the airplane, a power plant and drive mechanism for rotating said propellers, normally inoperative means for ren- (lering said power plant inoperative, and means disposed in and controlled by the slipstream of each propeller for actuating said means for rendering the power plant inoperative.v said slipstream Controlled means operated to actuate said means and render the power plant inoperative by the failure of the slipstream controlling the same, respectively.

32.. In 'a Vertical lift type of airplane capable of horizontal gliding fiight, propellers mounted laterally of the longitudinal axis of the airplane, a power plant for rotating said propellers, and mechanism controlled by the slipstream from each propeller for rende'ring the power plant inoperative to stop rotation of said propellers upon failure of any one of said propellers, the airplane formed with the center of gravity in relation to the other forces developed such that on stopping the rotation of said propellers the airplane automatically assumes horizontal gliding position.

38. In a Vertical lift 'type of airplane capable of Vertical fiight and of horizontal fiight, propellers mounted laterally of the longitudinal axis thereof, aerofoil surfaces mounted in the slipstream of said propellers and acted on thereby, asource of power for rotating said propellers, mechanism controlled by the slipstream from each propellei` forcutting off the power to stop rotation of all of said propellers upon failure in operation of any one of the said propellers, and the center of gravity of the airplane at a point forward of the force developed by the aerofoil surfaces, whereby upon cutting off of the power and stopping of said propellers, the airplane automatically assunies horizontal gliding position.

34. In aircraft, in combination, a propeller, and means Controlled by. the slipstream for rendering said propeller vinoperative under certain predetermined propeller conditions.

35. In aircraft, in combination, a plurality of propellers, and means controlled by the slipstream for rendering all of said propellers inoperative under certain predetermined propeller conditions.

36. In an aircraft propeller drive, apower unit, propeller shafts disposed at op osite sides of said power unit, a drive sha t extending between and operatively coupled to corresponding ends of said propeller shafts, saigeower unit operatively connected with said drive shaftvintermediate the propeller shafts, propellers mounted on the opposite free' ends of the propeller shafts, and an auxiliary drive shaft extending between, operatively coupled with and driven from and by said propeller shafts adjacent the propellers thereon,respeotive1y.

3 In an-aircraft proeller drive, a power unit, propeller shafts 'sposed at opposite i sides of the power unit, a drive shaft ex- .{endin I propel e between corresponding ends of the r shaft, gearing operatively coupling the drive 'shaft with the ends of said propeller shafts, respectively, to rotat-e said propeller shafts in opposite direetions, the power unit operatively connected with said drive shaft intermediate the propeller shafts, propellers mounted on the free ends of the propeller 'shafts, respectively, opposite the ends thereof coupled With said drive shaft, an auxiliary drive shaft extending between the propeller shafts adjacent the propellers thereon, and geai'ing operatively ooupling said auxiliary drive shaft With the oppositely rotated propeller shafts, respectively, said auxiliary drive -shaft driven from and by the said propellerI shafts.-

38. In an airplane including a body and day of Oct. 1924.

a power unit mounted within lthe body, a propeller drive embodying propeller shafts disposed at opposite sides of said body, a drive shaft extending transversely of the body and operat-ively coupled to corresponding ends of said propeller shafts,l a power shaft from the power unit to said drive shaft operatively co-upled therewith intermediate the propeller shafts, propellers 'mounted on the ends of said propeiler shafts opposite the coupling'of said shafts with the drive shaft, and an ,'auxiliary drive shaft extending between and operatively coupled with said propeller shafts adj acent the propellers thereon, the said auxiliary drive shaft operated by said propeller shafts.

Signed at Ithaca, New York, this 4th DOLPH F. HALL. 

